Spectrum is a range of frequencies, usually related in some fashion, but not always. Spectrum usually refers to the spectrum or range of light frequencies.

Russell
"The names of these particles is of no import here, but the fact that one end of cobalt atoms ejects big particles, and the other ejects small particles, is important. Also, the statement that it was never known before that one end of an atom is different from the other end is also important for it is not true. It has been known as long as electricity has been known that each end of a polarized body is different, and all matter is polarized. Each end of a balanced atom - which means equally paired - will emit the same sized particles from each end, because polarized, or divided pairs, are male and female and belong to the red and blue sides of the spectrum. The important fact that has been overlooked is the fact that an unbalanced particle of matter cannot emit equal potentials from both ends. [Atomic Suicide, page 274-275]